Kiyoshi Miyamoto* and Akinori Kosaku
Institute for Medical Science, Dokkyo University School of Medicine, 880 Kitakobayashi, Mibu, Tochigi 321-0293, Japan
*E-mail address: miyamoto@dokkyomed.ac.jp
(Received May 15, 2002; Accepted October 16, 2002)
Keywords: Structural Color, Shieldbug, Microtubercle, Mie Scattering, Multiple Interferences
Abstract. The microstructures of the elytron cuticle of the shieldbug Poecilocoris lewisi Distant that exhibits a distinctive structural color are examined by optical reflectance measurement, optical microscopy, and scanning and transmission electron microscopies. The yellowish-green area and the reddish-brown area of the elytron are covered in common with a superficial light-blue color. This color results from the scattering of light by small, transparent cuticular microtubercles with a cone shape. The microtubercles have a light wavelength size small enough to produce the Tyndall or Mie scattering effect. The scattering is more effective for the short wavelengths of incident light than the long wavelengths. Colors ranging from yellow to green are due to the reflectance of the multilayers system and dark pigment backing layer that acts as an absorber of the transmitted light. However, the reddish-brown striped area has a lower number of multilayers and lacks the dark pigment layer. The numerical models accurately predict the experimentally observed coloration.